Fluid pressure brake



March 12, 1935. w. E, DEAN 1,994,192

FLUID PRESSURE BRAKE- Filed May 20, '1951 I 4 Sheets-Sheet 1 INVENTOR.

WILLIAM E. DEAN A TTORNEY.

March 12, 1935. w DEAN 1,994,192

FLUID PRESSURE BRAKE Filed May 20, 1-931 4 Sheets-Sheet 2 INVENTOR.

WILLIAM E. DEAN ATTORNEY.

Fig.2;

March 12, 1935. w E, DEAN 1,994,192

FLUID PRESSURE BRAKE Filed.May 20, 1931 4Sheets Sheet 3 INVENTO WILLIAME. DEAN Q/M/W A TTORNEY.

March 12, 1935.-

w. E. DEAN 1,994,192 FLUID PRESSURE BRAKE Filed May 20, 1931 4Sheets-Sheet 4 Fig. 7

.f'ue n4 l we INVENTOR.

WILLIAM E. DEAN ATTORNEY.

Patented Mar. 12, 193

un ts-p STATES-'- 1,9944% FLUmrREssURE BRAK f William Edward Dean,Strathfield; Ne wjSouth Wales, Australia, assignorr to The WestinghouseAir BrakeCompanygWhfieidihg; Pa a corporation of Pennsylvania FApplication May 20, 1931, seriaiivdsasso lnGreat Britain MayZSQ 19307:01am; (o1. ace-s5) This invention relates to fiuidpressure brakingapparatus of the kind in which the supply of fluid to and its releasefrom the brake cylinder or cylinders of the apparatus is controlledby a5 triple or other form of distributing valvein: accordance withvariations in the-brake pipe pressure and has for its object to provideimproved apparatus of this character. H

The invention more particularly relates to apparatus of the abovecharacter in which an accelerating bulb orf chamber is provided intowhich fluid under pressure is arranged t be vented from the brake pipewhen the pressure in this pipe is reduced to effect an application ofthe brakes, the aotionof the bulbor chamber being to cause a localreduction in brake pipe pressure and thereby assistin the propagation,of the braking action throughout the train. It is evidently necessarythat-the fluid under pressure thus admitted to the accelerating bulb'orchamber should be wholly or partly released therefrom prior to the nextsuccessive or, a fure 1 connection with the operation of :the brakes;

The valve device may for examplebe arranged when actuated to effect alocal ventingfot the brake pipe to the atmosphere, in an emergencyapplication of, thebrakesor in the same'ciroil-Instances to effect thesupply of fluid under pressure from the brake pipe to the brake cylinderor other closed receptacle. v 1

According to a further feature of the invention the movement of thetriple or other form of dis* tributing valve to its release position,when the b-rakepipepressure is restored after an application of thebrakes in order, to effect their release,

is arranged to be accelerated and facilitated by temporarilyestablishing communication between the auxiliary reservoirandtheatmosphere or a suitable receptacle so as ton -produce: atemporary reduction in auxiliary reservoir pressure and thereby enablethe brake pipe pressure more readily to move the triple valve to itsreleaseposition. For this purpose the initial movement-oi the main slidevalve of the triple valve or preferably the initial movement of thegraduating valve is arranged to establish the communication abovereferred to between the auxiliary reservoir and theatmosphere orsuitable receptacle, this communication out oi i beiore the triple valveattains its iull release position'whereupon the auxiliary reservoirpressure restored to its norvaluein the usual manner by the supply offluid under pressure from the brake pipe or otherwise. i r

Fig, 1 is a, d ae anmlatic sectional view of a fluidpressure brake;equipment, embodying my invention; Fig. 2 a. sectional view of thetriple valve portion of the equipment shown in Fig. 1, showingthelmoving. in quick service position; Fig. 3 a view similar to Fig. 2,showing the triple; valve device inservice application position; a viewjsimilar to Fig, 1, but showing the moving parts in emergency applicationposition; Fig.5 illustrates an emergency vent valve brake cylinder; and7 a sectional view of a construction in which myinvention shown appliedtothe ordinary type of triple valve device.

' Referring now flrstto' the apparatus shown in Figure 1 it willbeseenthat the distributing valve I comprisesa triple or controllingvalve device A, a relay valvedevice Bra quick action valve device C and.a. vent valve device D.

The controlling valve device A comprises a main slide valve '1 providedwith a j graduating valve 2 containedin a valve chamber 3 and adapted tobe operated by a piston 4 contained in a piston chamber 5 which is incommunication with the brake pipe 6 of the apparatus through a; pipe andpassage'l; V v

The seat 8 of the slide valve 1 is provided with a, number ofports whichwill hereinafter be particularly; specifieduand which lead to a quickservice bulb 9, an auxiliary bulb 10, a supplementary reservoir 11,adummybrake cylinder 12, and the relay valve B, the auxiliary reservoir13 being in opencommunication with the valve chamber 3 through a passage14.

Therelay valve device B comprises a slide valve 15 contained in avalve:v chamber. 16 which is in open communicationwith the brakecylinder 1'? v of the apparatus through a; pipe and passage 18. Theslidevalvelfi is adapted to be operated by a piston 19 the lower face ofwhich is subject to'the pressure in a cylinder 20, the upper face of thepiston 19 being subject to the brake cylinder pressure in the chamber16.

The slide valve 15 is adapted to control communication through a port 21in the slide valve and a port 22 in the slide valve seat between thechamber 16 and a chamber 23 whichcommunicates through a'passage 24 witha restricted atmospheric outlet 25. V

The valve'device B also comprises a spring cone trolled supply valve 26controlling communication between the valve chamber 16 a1i'd a pipe andpassage 27 leading to a service reservoir 28.

The quick action valve devicefCcomprises a slide valve 29 containediniavalye phamber30 which is in open communication with the bulb, 9through a passage 31, theslide valve 29 being,

adapted to be operated by a pist'onj32 subjecton one side to thepressure in the chamber 30 and on the opposite side to the pressure in achamber 33 communicating by means ot a passage 34 withthe'brake'pipe"p'assage 'T. f

A restricted port 35 in the seat 'of-the slide valve 29 leads through apassage 36 to a restricted atmospheric outlet 37- and another port inthe slide valve seat l'eads'to a' 'passage 38 communicating with thevent valve deviceD. l

The vent'valve device D compr ses a spring con: trolled vent valve 39controlling communication between an outlet 40 and the-brake pipepassage 7,-the valve 39 'being'ada'pted to be" operated by a springcontrolled piston 41 subject on its lower side to the pressureobtaininginfthe passage38 and on its upper'sideto the pressure in achamber 42 communicating throug'h'aTstricted port 43 with the outlet'40.l

The dummy brake cylinder 12" is provided with a piston 44' subjecton itsouters'ide to the action of a spring 45, the cylinder 12 on' theopposite side of the piston 44.-communicat'ing through a passage 46 witha port in' th'e seat 8; of the slide Valvel.

In order to maintain "the -"graduatingivalve 2 closely in engagementwith the main slide 'valve 1 a cavity 119- is provided "leading througha pas sage 120 to an atmospheric port l2l-in the re5 lease'position ofthe'sl ide valve. f

The operationoi the apparatus is-asfollowszQ-- In Figure 1 theapparatusis sh'ovvn as in its 'release and charging position in which the fiuidunder pressure is being supplied irom the-brake pipe6 through passage 1;pasta non return ball valve 47 to a passage iBleading to arestrictedport 49 in the slide valve seat 8. Therice through a port 50 inthe-slide valve Ljfiuid is suppliedto a passage 51 in the graduatingvalve 2. A port in the graduating valve 2 '-communicati'ng-with thepassage 51* establishes communication through a port 52 in the slidevalve; 1 withapassage 53 leading to the supplementary- I reservoir 11, abranch passage 54 from the passage 53 leada ing to a restricted port'55'in the" slide 'valve seat 8. The port 55 communicates through a'passage56 in the slide valvel'with aport '57which, in the.

position of'the graduating'valveshown in Figure 1,' is open to thevalvechamber 3; The latter and the auxiliary'reservoir '1-3 are-thus" chargedwith fiuid under p'ressurei 'lhepassage 51 in the graduating valve 2also "communicates througha-port 58 witha passage '59 leading througha'restricte'd port60- to the pipe and passage 27 leading to'the servicereservoir28.

It will thus be seen that the auxiliary reservoir 13, the servicereservoir 28- and the supplementary reservoir 11 are all charged withfluid at brake pipe pre5sure 1,.f 2 7,

The brake cylinder 17 is in communication with the atmosphere by way ofthe'pipe and passage 18, valve chamber 16 of the relay valve device B,ports 21 and 22, passage'24 and atmospheric outlet 25. The bulb 9 is incommunication with the atmosphere by way of passage 61, a cw,

ity 62in the slide valve 1 and a passage 63 leading to the passage 24,any fluid under pressure in the auxiliary bulb 10 being vented to thepassage 61 past a non-return ball valve 64. The

valve 1, cavity 69 in graduating valve 2, port 70 and passages '71 and24. 1 v

In order to efiect a service applicatio niof the -brakes,'the brake pipepressure is reduced-in the usual manner so as to cause the piston 4 tomove upwards; carrying with it the graduating valve 2.

Communication between the brake pipe 6 and the service reservoir 28, thesupplementary resat the portsleading to' the cavity 51.Communicationbetween the passage 67 leading to the cylinder 20 and dummybrake'cylinder 12and the atmospheric passage 24 is also cut offatthe'cavity 69 :andportslGB, 70. This movement of the graduating valve 2also closes the port 57 an'd'f cation is established as shown in Fig.2,between the passage leading to the passage 48 anda port '76communicating by a passage 77 with the cavity 62. In this position ofthe slide valve 1 thegcavity 62 registers with ports 78, '79'leadingrespectively to the passage 61 and to a passage auxiliary bulb 10. As are'sult fluid. from the brake pipe 6 flows to the'bulb 9 by way of pas-.80"leading through a restricted port 81 to the 1 sages '7, 48,and"75,-port '76, passage '77, cavity.

62 port .78'and passage'6l andifromcavity 62 to the bulb 10through'port'IQ, passage and restricted port 81. 1

It will be observed that the upward movement of theslide valve 1 abovereferred to has cut: off communication between the passage 63 leading tothe outlet 25 and the cavity 62; v V The brake pipe 6 is thus locallyvented directly into the mainbulb 9 and through a restricted port intothe auxiliary'bulb 10 with the result 7 that the reduction in brake pipepressure is propagatedand accelerated'throughout the train in the wellknown manner.

The continued upward movement of in Fig; 3 injwhich it. engages with theusual :spring controlled stop 82 in the chamber 5 establishescommunication between the port 74 and the'pi ston '4 to its serviceapplication position as shown:

pressure from the'auxiliary' reservoir'13 and the Valve chamber 3 issupplied to the cylinder 20 of the relay valve deviceB by way-of ports.72 and '74 and passage 67. Piston 19 consequently moves upwards cuttingoff communication between the 1 chamber 16 leading to brake cylinder 17and the atmospheric passage 24 at the ports 21, 22 in the 1 slide valve15. During its upward movement the; piston 19opens the supply valve'26so that fluid under pressure is supplied from the service res- I 'ervoir28* to the brake cylinder '17 by way 'ofjpipe- V 27, chamber 16 and pipeand passage 18. i V In the serviceapplication position of the slidevalve 1 the fluid flows from the auxiliary reserthe passage 67 with theresult that fluid under I voir 13 not only to the cyllnder 20 as 'abovede scribed but also to the dummy brake cylinder 12:by way of'passage 67,"cavity wand. passage 46 so that the piston 44 "is moved outwardsagainst its controlling spring 45;.

The reduction in the pressurein theauxiliary reservoir (which isofrelatively small capacity) dueto flow ofjfluid to the cylinder'20 and tothe dummy brake cylinder lz'causes the piston 4 to move to its 'servicelap position in which the port '72 in the slidevalve lis covered by thegraduating valve 2, the supply of fluid to the cylinders 2 and 12 beingthus interrupted. w

The supply valve: 26 is maintained in its open position as aboveexplained untilthe brake cylinder pressure in the chamber lfi attains avalue sufficient to cause a downward movement of the piston 19 acting inoppositionto the pressure of theufiuid in the cylinder 20 whereupon thesupply valve 26 closes and the further supply of fluid to the brakecylinder l'Zirom the service reservoir 28 is cut off. Successivefurther-reductions in brake pipe pressure will evidently cause a furthersupply of fluidto the brake cylinder inasimilarmanner'. t'

' In order to graduate the release of the brakes,

the brake pipe pressureuis increased: with the result that the'piston 4and main slide valve l are moved downwards to'the release position shownin Figure 17in which the-release of fluid from the cylinder 20 andfrom'the'dummy brake cylinder 12 is efiected by way of the-passage 6'7,port 68, cavity 69,:port -.'Z0 and passages 71 and 24. The consequent.reduction in the fluid pressure in the cylinder 20 permits the piston 19to move downwards tothe position shown under the action of the brakecylinder pressure in the chamber 16 so that fluid released from. thechamber 16,.and the lbrakexcylinder 1'7 through the ports 21, 22 and thepassage 24.

The pressure in the auxiliary valve chamber 3 is restored to theincreased brake pipe pressure by, flow, of fluid from the supplementaryreservoir 11 through passages 53, 54,v 56 and port 57 and as soon as thepressure in the valvechamher 3 slightly exceeds-the brake pipe pressurein the piston chamber the piston 4 again. moves upwards to close the.portafi'l and to interrupt the further supp of fluid-to thechamber 3.The release of fluid from the, cylinder, 20 by way of the cavity 69 isalso interrupted by the move! ment of the graduatingJVaIve-Z so thatwhen the brake cylinder pressure 'inLthe chamber 16 has beencorrespondingly'reducedythe piston 19 and slide valve moves-upwards; tocut off the further release of fluid: from the brake} cylinder throughthe ports 21, 22. a

In order to fully release thebrakcsithe brake pipe pressure isincreased'to the normal standard pressureand the triple-pistonAisthereby moved, to release positionipwhere it ,remains. Fluid underpressure is then released from the brake. cylinder through the relayvalve device 85, communication is established between the bulb9 and theatmosphere by way of the passage 31, chamber 30, a port 89, restrictedport 35, passage 36'and the restricted outlet 37. The capacity of theoutlet 3'7 is such that the rate of fiowof fluid from the bulb 9 to theatmosphere under these conditions is substantially the same as the rateof reduction of brake pipe pressure in a service application.

T When a heavy reduction in brake pipe pressure is effected to cause anemergency application of the brakes the piston 4 is moved upwards to itsfull extent displacing the spring-controlled stop 82 as shown in Fig. 4.

During the upwardmovement of the piston 4 the main bulb 9 is chargedwith fluid under pressure from the brake pipe 6 as in a serviceapplication as above'described the fluid in the bulb 9 being utilized tooperate the vent valve device D as will be hereinafter described.

- In the final position of the slide valve 1, th valve chamber 3 is incommunication with the passage 67 leading to the cylinder by way of apassage 83' and a port 84 in the slide valve 1 and since the port 84is'not controlled by the graduating valve 2, it will be evident that thepressures'in the auxiliaryreservoir 13 and the cyIinder ZO will equalizeso that the piston 19 will move upwards and maintain the supply valve 26open so a's'tc supply full service reservoir pressure to the brakecylinder 17. V Referring now to the action of the quick action valvedevice C and the vent valve device D in an emergency application of thebrakes the rapid reduction in brake pipe pressure causes the pressure inthe chamber 33 to be reduced more rapidly than the rate of reduction ofpressure in the bulb 9 by Way of the restricted outlet 37 with theresult that the piston 32 moves upwards beyond its service applicationpositioncompressing the spring-controlled stop 85, to a position inwhich a port 86 leading to the passage 38 is uncovered by the slide'val-ve 29. Fluid from the bulb 9 is thereuponsupplied through passage31, valve chamber 30, port 86 and passage 38 to the underside of thepiston 41of the vent valve'device D with theresult that the piston 41moves upwards opening the vent-valve 39 and permitting the releaseof'fluid from the brake pipe 6 by way of passage- 7and exhaust outlet40. f l

The fluid under pressure beneath the piston 41 isgradually released tothe outlet 40 through a port 8'7 in the piston 41 and the port 43leading from. the chamber-42 so thatafter an interval of time the ventvalve 39 is reclosed under the action of its controlling spring 88.

The reduction in the pressure in the bulb .9 due to the flow of fluidtherefrom as above described causes the piston 32 of the quick actiondevice C to return, under the action of the spring controlled stop 85,to itsservice application: position' in which the port 89in the slidevalve 29 registers with the restricted port 35 with the result that thebulb 9 is vented to the atmosphere by way of passage 31, chamber 30,ports 89 and 35, passage .36 and atmospheric outlet 3'7 As soon as thebulb 9 has been completely yented, the brake pipe pressure in thechamber 33 causes'the piston 32 to return to the position shown in Figue 1; r r

When tlie brake pipe pressure is restored to effect a release of. thebrakes after anemergency application as above described the piston 4first moves the graduating valve 2 to open the port'57, thesubsequentinitial movement of the slide valve 1 establishingcommunication betweenthe pas! sage 56 and the port .78. Fluid under:pressure from the valve chambers and the auxiliary reservoir 13-is thusventedto the empty bulb 9 by way of the port 57, passage 56, port .78and passagefil.

Adefinite limited reduction in auxiliary reser.-. voirpressureisthus-eiiected so'that axgreater differential pressure acts onpiston 4, whichfacilitates the return of the piston 4to its releaseposition as the brake pipe pressure is increased to its normal value. II I II t It will be understood that theoutlet 40 of theventvalve'deviceD may be arranged to com: municate directly with theatmosphere, as shown in Fig. 1,0! with ,a suitable closedreceptacle 200,as shown in Fig. 5, sc as to: limit the extent of brake pipe pressurereduction. Furthermorethe outlet 40 may if desired be arranged tocommunicate with the .brake cylinder 17, as shown in Fig. 6, so as tosupply iiuidunder pressure from the brake pipe. to the brake cylinderapplication of the brakes. I I

From the abovedescription it will beappreciated that inthe'apparatusillustratedin Figure 1, the quick service bulb 9 isutilized in a double capacity to efiect a-rapid emergency application ofthe brakes the bulb 9 being first utilized as a receptacle into whichfluid from the brake pipe is vented and the fluid thus supplied to thebulb beingsubsequently utilized to operate a valve device to effect afurther release of .fiuid under pressure from the brake pipe. I V IReferring now to Figure .7. the invention is illustrated as applied to awell-known type of triple valve embodying a regulating valve forcontrolling therate of flow offluid to the brake cylinder during abraking application in such a manner that this flow-is restricted duringpart of the period of supply of fluid. I The triple'valve piston 4 isadapted toactuate a graduating .valve 2 and a mainslidevalvel theiseat 8of which is provided with the usual service port- 90, exhaust port 91,and a brake. cylinder port 92lea ding to the brake cylinder passage 18-thesethree ports being indicated in dotted lines in Figure'l,v v

The seat 815 also provided with a port 93 leading to a chamber 94 abovethe regulating valve element 95, aport;9 6.leading through a passage 97to the auxiliaryzbulb 10; a-port 96 communieating with a passage 99leading through a non;- return ball valve 100 to the main bulb 9 and aport 101 communicating with the piston-chamber 5.. I

The slide valve 1 iszprovided with a port 102 communicating with. acavity 103adapted to register with the port 90, a cavity 104, .a cavity105, provided .with a port :106,:and-a'port 107. The graduating valve 2is provided with ports 108, 109 communicating with one another'through apassagel10 The regulating valve-element 95 comprises a valve 111provided'witha controlling spring 112 and having a central restrictedport 113 establishing communicationbetween the chamber 94 andthebrake.cylinderjpassage 18. The valve 111 is arranged to beoperated'by a flexible diaphragm 114 provided with a head 118, thediaphragrh 114. separating the chamber. 115 containing the valve 111 andspring 112 iromthe chamber 116 inopen communication withthe bulb 10,

in an emergency the chamber Ila-being in :open communication With the1passage,18. .j.

,The operation ofithe apparatus shownin-Fig 1 ure 7 is .as,follows:.

Under charging or release conditionsthe par-ts a cavity (notshown). inthe-slidevalve Land.

the exhaust. port .91. The bulb-10 is .in communication with theatmosphere byway of passage 97,

port 96, cavity= j104-,- port.93,,past;the.valve 111 (which isnormallysmaintainedopen under the action-of the spring 112) chamber 115and the passage 18. The main bulb 9 communicateswith the atmospherethrough .the restricted port interposed between the bulbs 9 and:10.

In order to efiect an. application of the brakes the brake. pipepressureisreducedin the'us'ual manner and the consequent initialmovementof graduatingvalve 2:to registerzwith the ports 106 and 107 respectivelyin the main slide'valve 1. Fluid thereupon flows from the piston chamber5 to the bulb 9 byway of ortsw 101, 107, 109, passage 110, ports.1082and' 106,: cavity 105, port 98 and passage '99 ther'ebyeffecting areduction in .the pressure in the'pistonchamber 5 and accelerating themovement of the piston .4 to its application position; 1 1 I Owing .tothe relative positions of the ports 101 and 107 it Willb'e. seen: that.the communication above described between the-chamber '5 and the bulb 9is maintained during th'efinitial movement of the. main slide valve 1 asthe'piston 4 moves towardsthe right;

I Uponinitial movement of the'graduating valve 2, the port -102:isuncovered and upon movement I of the main slide valve l to serviceapplication position, the port 103, .which opens to-port .102,

registers with passageQO, which opens into charnber 94, so that fiuidunder pressure is 1 supplied 25: the piston 4, causesthe' ports .108,109 in the from the auxiliary 'reservoirito th'e brake cylin..

der by Way of valve chamber 3 .to chamber 94 andrthence past *the: openvalve" 111, chamber 115 and passage 18'. The supply-of fluid to'thebrake cylinder. as above described constitutes the so called quickinshot and effects the rapid l the well known'manner. I I

. During the continued movementof the piston application of the brakeblocks to the wheels" in 4 the cavity establishes direct communicationbetween the ports same 101 and fluid under pressure from the chamber 5is freely supplied: to the bulb 9. Asthelpressure in thebulb 9 is thusbeing built up,ffi uidfiow's"from the bulb"9*to the bulb 10' through'therestricted port81 and as soon as the pressure in the bulb 10 attainsaT.

predetermined value the valve 111 is closed by the fluid pressure in the'chamber 116: acting 1 upon the diaphragm 114 in opposition; to thespring 112; Afterthe' valve l l'l has ithusbe'e'n closed, furthercommunication between the chamber 94 and the chamber llfi'canonlylo'ccur through the restricted port113 inithe. valve 111 f Iuntil the brake cylinder pressure in the cha f ber 115 hasattainedavaluesufiicifent toio vercome the pressure in "the chamber;11 andregpenther lvellt. I

It will thus be seen that the regulating valve 111 is normally open andis closed assoon as pressure is built up in the bulb 10, the valve,

the bulb 10 and chamber 116 by flow from the brake pipe.

In the full service position of the slide valve 1, communication betweenthe bulb 9 and the piston chamber is still maintained through the cavity105 but return flow of fluid from the bulb 9 to the brake pipe-isprevented by the ball valve 100 so that the fluid pressure in the bulbacts continuously upon the diaphragm 114.

The reduction in the pressure in the valve chamber 3 by flow of fluidunder pressure therefrom causes the piston 4 to move to its lap positionin which the graduating valve 2v covers the port 102 and thus cuts offthe further supply of fluid to the brake cylinder.

The release of the brakes is effected in the usual manner by therestoration of the brake pipe pressure towards its normal valuewith theresult that the piston 4 returns to the release position shown in Figure'7 in which fluid from the bulb 10 is vented to the atmosphere by way ofthe passage 9'7, port 96, cavity 104, port 93 and the brake cylinderpassage 18.

The invention is evidently not limited to any of the particularconstructions of valve mechanism above described and illustrated and maybe embodied in or applied to any suitable type of triple or distributingvalve adapted for fluid pressure braking apparatus for passenger orfreight service with or without light and load braking adjustments. I

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is:--

1. In a fluid pressure brake, the combination with a brake pipe, a brakecylinder, and a triple valve device operated upon a reduction in brakepipe pressure for supplying fluid under pressure to the brake cylinder,of means operated upon a reduction in brake pipe pressure for ventingfluid from the brake pipe to a chamber, and a regulating valve devicefor determining the rate at which fluid is supplied to the brakecylinder, and operated by fluid supplied from the brake pipe to saidchamber.

2. In a fluid pressure brake, the combination with a brake pipe and abrake controlling valve device operated upon a reduction in brake pipepressure for effecting an application of the brakes, of means operativeupon a gradual re duction in brake pipe pressure for venting fluid fromthe brake pipe to. a chamber, and valve means subject to the opposingpressures of said chamber and the brake pipe and operative upon a suddenreduction in brake pipe pressure for effecting a venting of fluid fromthe brake pipe.

3. In a fluid pressure brake, the combination with a brake pipe and abrake cylinder, of a brake controlling valve device operative upon agradual reduction in brake pipe pressure for supplying fluid underpressure to the brake cylinder and to a chamber and operative upon asudden reduction in brake pipe'pressure for supplying fluid underpressure only to the brake cylinder.

l. In a. fluid pressure brake, the combination with a brake pipe and abrake cylinder, of a relay valve device operated by an increase in fluidpressure for supplying. fluid under pressure to said brake cylinder, adummy brake cylinder,

and an equalizing valve device operated upon a gradual reduction inbrake pipe pressure for supplying fluid under pressure to said brakecylinder and said dummy brake cylinder and opera-v tive upon a suddenreduction in brake pipe pressure for supplying fluid under pressure onlyto said relay valve device.

5. In a fluid pressure brake, the combination with a brake pipe, of areservoir and a brake controlling valve device subject to the opposingpressures of the brake pipe and said reservoir and operated upon asudden reduction in brake pipe pressure for venting fluid from the brakepipe to a chamber and upon a subsequent increase in brake pipe pressurefor venting fluid from said reservoir to said chamber.

6. Ina fluid pressure brake,'the combination with a brake pipe, of areservoir and a brake controlling valve device subject to the opposingpressures of the brake pipe and said reservoir and operated upon asudden reduction in brake pipe pressure for venting fluid from the brakepipe to a chamber, and valve means operative by fluid vented from thebrake pipe to said chamber for efiecting a venting of fluid from thebrake pipe, said brake controlling valve device being operative upon anincrease in brake pipe pressure following a sudden reduction inbrakepipe pressure for venting fluid from said reservoir to said chamber.

'7. In a fluid pressure brake, the combination with a brake pipe, of areservoir and a brake controlling valve device subject to the opposingpressures of the brake pipe and said reservoir and operated upon asudden reduction in brake pipe pressure for venting fluid from the brakepipe'to a chamber, and valve means operative upon a sudden reduction inbrake pipe pressure by fluid vented from the brake pipe to said chamberfor effecting a venting offluid from the brake pipe, means for slowlyventing fluid from said chamber as supplied from the brake pipe, saidbrake controlling valve device being operative upon an increase in brakepipe pressure following a sudden reduction in brake pipe pressure forventing fluid from said reservoir to said chamber.

WILLIAM EDWARD DEAN.

